Automatic telephone apparatus and circuits



- May 5, 1942. G. R. EATON 2,281,564

AUTOMATIC TELEPHONE APPARATUS AND CIRCUITS Filed Sept. 10; 1938 s Sheets-Sheet 2 May 5,1942 G R EA ON 2,281,564

AUTOMATIC TELEPHONE APPARA'IUS AN, CIRCUITS FiIed Sept. 10, 1938 6 Sheets-Sheet 3 J FIE].

iii/F175:- 201.; 51 55575? y 1942- G. R. EATON I 2,281,564

AUTOMATIC TELEPHONE APPARATUS AND CIRCUITS Filed Sept. 10, 19:58 6 Shets-Sheet 4 TO LINE-Z JUL/227701! EDFgEHEEYHZ LINE IO May 5,1942. (5. R. EATON AUTOMATIC TELEPHONE APPARATUS AND CIRCUITS Filed Sept. 10, 1958 6 Sheets-Sheet 5 JUL/E27 472':

EEUPgE'HE'EYETI i w w y 1942- Q G. R. EATON 7 2,281,564

AUTOMATIC TELEPHONE APPARATUS AND CIRCUITS Filed Sept. 10, 1938 6 Sheets-Sheet 6 JUL/m v ,E'Pafg'efi E5752? H2757.

Patented May 5, 1942 AUTOMATIC TELEPHONE APPARATUS AND CIRCUITS George R. Eaton, Oak Park, Ill., assignor to Kellogg Switchboard and Supply Company, Clucago, 111., a corporation of Illinois Application September 10, 1938, Serial No. 229,266

41 Claims. (01. 179-24) This invention relates to an improvement in automatic telephone apparatus and circuits of the type used to establish connections between the lines of a calling and a called telephone subscriber.

The automatic telephone apparatus which has been generally used, heretofore, has been of two kinds. In one, traveling brushes are arranged to be moved over a series of groups of contacts to select a desired group of contacts corresponding to the line or trunk desired. The other system, at present employed, establishes the desired connections through the medium of gang relays which are controlled and energized in coordinate fashion to establish the connection.

The present invention seeks to combine in a unitary structure the advantageous features of both the prior systems above referred to.

The object of the invention is the provision of a line connecting mechanism which is compact, durable and reliable in operation and cheap to manufacture.

One of the features of the invention resides in the provision of a series of groups or stackups of contact springs which may be similar to those of a gang relay and the provision of selective means, whereby the springs of any desired stackup may be actuated by a single electromagnet. The function of the sets of contact springs may be, in some respects, similar to those of the relays used in establishing connection in the allrelay systems, with the difference that in the prior art, with which applicant is familiar, the operating magnet has been arranged to operate all the sets of springs of a group while, in applicants device, a single magnet, common to all contact springs of the relay, may be caused to selectively actuate any desired set or stackup oi springs in the group.

Another feature resides. in the selecting means and operating circuit therefor, whereby the same control apparatus may be employed in joining the connecting link to either a calling or a called line.

A still further feature, closely related to that just mentioned, resides in the'arrangement by means of which a set of springs of one group may establish connection to a calling line and a set of springs of another group, arranged to be selected by the same mechanism, may contemporaneously provide connection to a called line. The abovementioned calling and called line may, in some cases, be united into a single telephonic or other circuit through the instrumentality of con- In one form, the present invention contemplates the provision of four or more groups of contact spring stackups, a single actuating electromagnet being provided for each group of springs and selecting mechanism common to the several groups of springs, whereby any desired set of contacts in any one of the several groups may be selected and then individually operated by the actuating magnet associated with that group of contact sets.

Other features and advantages will appear from time to time as the description of the invention progresses.

It is believed the details of the invention will be most readily understood from a detailed description thereof, taken in connection with the accompanying drawings in which Fig. 1 is a plan view showing one group of contact springs and the selecting mechanism associated therewith;

Fig. 2 is a view of the structure shown in Fig. 1 as seen from the bottom of the page;

Fig. 3 is a view similar to Fig. 1, with parts omitted, but showing the commutator mechanism at the right and the stackup selecting mechanism in actuated position;

Fig. 4 is a side view of the motor mechanism by means of which the selecting apparatus is actuated;

Fig. 5 is a cross-sectional view taken through Fig. 1, showing one set of springs and the actuating mechanism associated therewith;

Fig. 6 is another section through the apparatus of Fig. 1, showing further details of construction;

Fig. 7 is a view looking at the end of one of the group contact sections and showing the shift magnet which cooperates with the selecting mechanism shown in Figs. 1 and 2 to actuate'a single set of contact springs. In Fig. 7, the springs are shown in actuated position;

Fig. 8 is a cross-sectional view through the apparatus of Fig. 1 showing a group of contacts in, actuated position; v

Fig. 9 is a detached view of one of the cam discs, forming part of the selecting mechanism;

Fig. 10 is a fragmentary view of the contact actuating magnet and its armature structure;

Fig. 11 is a view of the mechanism of Fig. 10 as seen from the bottom of the page;

Fig. 12 shows the cams of the commutator in detached relation, and

Figs. 13, 14 and 15, with Fig. 14 to the right of Fig. 13 and Fig. 15 below Fig. 13, schematically indicate circuits illustrating the method of operation of the switch.

Reference will now be made to the drawings in which like reference characters indicate the same parts in each of the several views. In Fig. l is shown a single selecting group relay, with the exception of the commutator springs which are shown in Fig. 3. A different view of the same mechanism is shown in Fig. 2. From reference to the drawings, it will be noted that there are ten sets or stackups of springs which in Fig. l are designated as a a a etc., to a and by reference to Fig. 2, it will be seen that each of the stackups, as a a etc., comprises three pairs of springs although, obviously, the number may be increased or decreased as desired. Extending adjacent to and underlying the ends of the springs a a etc., is a plate H] which is slidably mounted on the screws H, extending through slots 12 in plate It. Pivotally supported on the plate III by means of screws I3, are ten selecting arms l4, one for each stackup, which are normally maintained in the positions shown in Fig. 1 by means of the respective springs I 5. Extending across the front of all four of the selecting relays and the commutator springs shown in Fig. 3, is a shaft or rod I6. Fixed on the rod l6, opposite each relay, are ten discs l1, one for each arm 14 and stackup a a etc. Each of these discs is provided with an offset or cam portion 18. These cam portions I8 are spirally arranged about shaft (6 at intervals of approximately 32.7 degrees. In other words, shaft It has eleven positions-a normal or home position for which there is no corresponding cam l8 and ten actuating positions in each of which a cam 18 is positioned opposite one or another of the laterally extending lugs 19 at the free ends of levers I4. E1ectromagnetic means, subsequently to be described, are provided for shifting plate to the right, as shown in Figs. 1 and 2. It is now obvious that, as one of the cams I8 is opposite the projecting lug I9 corresponding to the selected stackup a a etc., as the case may be, the selected lever I4 will be rotated in a clockwise direction about its supporting screw l3, against the tension of its spring I5, and the inner end thereof, will be placed under the lowermost spring of the selected stackup, as shown in Figs. 3 and 8 of the drawings. The inner end of each of the levers I4 is provided with a groove 20 which receives a projecting stud of insulating material 2| on the lowermost spring of the stackup.

Pivotally supported under the sets of springs a a etc., and extending the entire length of the relay is a plate 22 having fixed, thereto, an armature 23 extending adjacent to a common operating magnet O. Screws I I, on which plate 10 is slidably mounted, have their screw-threaded ends received by threaded openings in plate 22 so that plate I0 is tilted whenever magnet O is energized but is mounted for limited longitudinal movement, relative to plate 22. A spring 25 having one end attached to plate I!) and the other end attached to plate 22, tends to move plate [0 to the left as seen in Figs. 1 and 2.

The means for rotating shaft I6 is best seen in Fig. 4. Fixed to shaft H5 is a ratchet wheel 26 arranged to be engaged by pawls 21 and 28, fixed to arm 29 in any desired manner. Arm 29 is piv- P otally supported by pivot pin 30 and is arranged to be engaged by the laterally extending end 3| of the armature 32 of actuating magnet M. From an inspection of the drawing, it will be obvious that when magnet M is energized, armature 32 will be drawn into contact with the core of the magnet, causing the right end of arm 29 to move upwardly. Pawl 28, which is in engagement with one of the teeth 34 of ratchet wheel26 will now operate to rotate shaft [6 one-half step or approximately %2 of a complete revolution. Upon the deenergization of the magnet M, spring 35, one end of which is fixed to arm 29 and the other fixed to the magnetic circuit member 36, acts to draw arm 29 downwardly, and pawl 21 engages a tooth on the opposite side of ratchet wheel 26 to complete the rotary step of shaft l6. Thus, the shaft l6 will be rotated one step or approximately A of a complete revolution each time the actuating magnet M is energized and deenergized. Except when the selecting mechanism is in its normal position, each step will act to place one or another of the cams l8 opposite a projecting portion I9 of an arm l8 so that the corresponding contact stackup a a etc., or whichever it may be, will be actuated, as shown in Fig. 8 of the drawings, as a result of the energization of the common magnet 0.

At H2 in Fig. 13 is schematically indicated what I term a commutator. The actual mechanism employed is shown at the right in Fig. 3 of the drawings. This commutator comprises ten pairs of contact springs 31, one pair for each operative position of the shaft [6, which pair is closed whenever the shaft It occupies a position corresponding to the spring pair. Only five pairs of springs 31 are shown in Fig. 3, but it is to be understood that five other pairs of springs are located directly below those shown. Positioned on shaft it, between each two pairs of springs 31, is a disc 38, having a cam projection 39. These cams are shown in their relative positions in Fig. 12 and they are so arranged as to close a pair of springs 31 in each operative position of shaft 16, all of earns 39 as well as cams [8 being inoperative when the shaft is in its eleventh or inoperative position.

In Fig. '7 is shown the means for shifting plate l0 laterally at the time a connection is to be 7 made. Extending downwardly from plate It! is a pin 49 arranged to be engaged by the arm 4| extending at substantial right angles to armature 42, pivotally supported on pin 43. An electromagnet S is associated with armature 42 and upon its energization, arm 4| engages pin 40 and moves plate ID to the right, as seen in Figs. 1 and 2 of the drawings. Armature 42 is provided with a lug 45 of insulating material adapted to engage spring 46 and move it into engagement with contact spring 41 when a magnet S is energized. Shift magnets such as magnet S are shown at S S S and S in Figs. 13 and 14. Contact spring 46 is, in like manner, shown at 46a, 46b, 46c and 46d in Figs. 13 and 14.

A very simple expedient is provided .for quickly and accurately positioning the various cams on the shaft I6. Shaft 16 is provided, along one side, with a groove or keyway arranged to receive a bar or rod 48 which forms a spline or key. The various discs, such as the cam discs I! and the commutator discs 38 are provided with eleven equidistant notches 50, as shown in Figs. 9 and 12. Thus, all of the cams I! may be made alike and all of the commutator cam discs 38 may be formed alike. In mounting the discs, as for instance the discs I I on the shaft 16, it is only necessary to slip the successive cams one notch to secure the necessary spiral arrangement of the cams on the shaft. The cam discs 38 may also be mounted in the same manner, being slipped one notch 50 for each cam added to the shaft. Thus, after the first cam disc I! of the group has been correctly placed on the shaft in relation to the discs 38, the other discs IT may be added in an obvious manner. Spacers 5| are provided between the various cam discs to maintain them in the proper spaced relation.

The sequence of operations of the contact stack selecting mechanism, above described, isv as follows: Shift plate will be moved to the right by magnet S, shaft IE will be rotated through the medium of the mechanism, shown in Fig. 4, to a position corresponding to the desired spring stackup, whereupon common actuating magnet 0 will be energized. The energization of magnet 0 will tilt plate 22 and shift plate In carried thereby, into the position shown in Fig. 8. One of the arms 14 will have been rotated in a clockwise direction by means of the operative selecting cam l8, as best seen in Fig. 3. All of the arms l4, except the one corresponding to the operative cam I8, will be in a position such that they will pass idly between the successive contact stacks, as shown in Fig. 3. The selected arm l4, however, will underlie its contact stack and the groove 28 at the inner end thereof will receive the end of the insulating pin 2| carried by the lowermost spring, as indicated in Fig. 8. In the normal operation of the mechanism, the common magnet 0 will remain energized during a connection. The selecting mechanism, comprising the shaft l8, and the apparatus associated therewith, as soon as it has performed its function, will immediately return to its nor mal position so it may be used in the establishment of another connection. In other words, the selecting mechanism is tied up only so long as it is actually being used in establishing a connection. The groove or notch 20 at the end of lever 14, will serve to prevent the anti-clockwise rotation of the operative lever I4 by its spring- I5 and thus will hold the connection.

Before giving a detailed narrative of the operation of the switch and system by reference to the circuit drawings of Figs. 13, 14 and 15, a brief outline of the manner in which the switch functions, will be given. When a subscriber calls, the switch stepping magnet M will have a circuit completed which will cause the magnet to be intermittently energized and deenergized until a pair of springs 31, corresponding to the calling line, are closed through the medium of one of the cams 39. Thereupon, the stepping magnet will be deprived of current and shaft IE will cease rotating. shifted to the right as viewed in Figs. 1 and 2. When shaft I5 ceases to rotate, magnet O corresponding to the relay, will be actuated'and cause one of the stackups a a, or a whichever it' may be, corresponding to the calling line, to be actuated. The calling line will then be connected to one of the two link circuits herein provided. As soon as the selected stackup has been actuated, stepping magnet M again receives current and immediately returns to its normal or 11th position. Upon receiving a dialing tone, the calling subscriber will operate his dial in accordance with the number of the wanted subscriber. As the present disclosure provides for only ten lines, but one operation of the dial will be necessary. The stepping magnet M will follow the dial and will step shaft [5 into a position corresponding to the line that is called. Again, as previously mentioned, plate It] has been shifted to the right and magnet O of the relay at the terminating Plate has previously been wanted line. The wanted line will be'tested, and if found idle, it will be rung. Upon response of the called'subscriber, the two lines will be connected for conversation, magnets O of the two relays employed being maintained energized solong as the connection exists. The selecting mechanism comprising shaft l6 and the parts directly associated therewith, are always released and restored to normal position immediately after a magnet O of one of the relays is actuatcd.

Should 'a call be made by another one of the subscribers, the apparatus will function exactly as just described, except the circuits will be arranged so as to cause the energization of the magnet O of the relay A or B, not in use. As relay A is connected to relay C, and relay B is joined by its connecting circuit to relay D, when the second calling subscriber operates his dial, the relay C or D, corresponding to relay A or B used to select the line, will of course, be actuated to complete the circuit through the connecting circuit to the wanted line called by the subscriber who called second.

When the conversation is completed and the subscribers hang up, the two magnets O, which were maintained energized, are deprived of current and the relay mechanism rest/ores to its normal position.

We will now trace the establishment of a connection from a calling subscribers line to a called subscribers line. We will assume that the subscriber on line I desires to establish a conversational circuit to the subscriber on line It.

It may be here explained that the heavilyshaded conductors inFigsJlB, 14 and 15 indicate the talking circuit between-the subscribers after the connection hasbeen established. This circuit includes contacts in the set a of relay A and contacts in set 0 of relay C. Each line has a set or stackup of contacts in each relay. Thus, the contact sets 41 b 0 and d are individual to line i. Line I may be seized as a calling linethrough the contact set a or b as the case may be, and it may be seized as a called line through one or the other associated sets 0 or 01 individual to line 3- and so on for all the other lines. The subscriber on line I, upon removing his receiver from the hook in the usual manner, will establish a circuit from battery through the upper winding of line relay H0, back contact'of cutoif relay Ill, conductor L through the substation apparatus, back over conductor L through the other armature and contact of cutofi relay H! and through the second winding of relay H t, back to battery. Relay H0 attracts its armature. This removes groundfrom that one f the contacts lid of the commutator 2 which.

As previously explained,

times, except when the line is initiating a call The sequence commutator springs BFof'Fig. 3

-' "When line relay H0 attracts its armature, it

endofthelinkcircuit will be energized to close; the'contacts of thesta-ckup corresponding to the In like manner, contact sets a ,'b c and 1:1 are individual to line 2; sets a b 0 and d connects ground to start conductor II5 completing a circuit from'ground through-normal contacts I 2I of relay IOI, armature I20 and back contact of relay I02 and through the winding of relay I03 to battery and ground. Relay I03v attracts its armature which completes a circuit for the selecting mechanism motor magnet M which may be traced from grounded battery through the winding of magnet M, conductor '6, armature H1 and back contact of relay I05, armature H3 and back contact relay I02, armature H9 and front contact of relay I03 through armature I20 and back contact of relay I02, contacts I 2I and over conductor II5 to ground through the contact of line relay H0. Motor magnet M is energized and moves the wiper I I3 one step in an anti-clockwise direction which places it in engagement with the contact corresponding to the calling line. As the line relay I I is energized, the corresponding contact H4 is not connected to ground. Thus, motor magnet M will cease to operate and shaft I6 will come to rest in a position corresponding to line I.

When the shaft of the selecting mechanism moved from its normal position, the off-normal contacts ON were shifted so as to close contact I22 to ground and shift contact I23 from the position shown in the drawing to its alternate contact. Upon the closure of contact I22, a circuit was closed from ground through contact I22, armature I65 and front contact of relay I03, normal make-before-break contacts I66 of relay I02 and the winding of relay I02 to battery and ground. Relay I02 is energized and closes an alternate path for its winding from battery through the winding; armature I61 and front contact of relay I02, armature I68 and back contact of relay I to brush II3.

If, now, some line other than line I was calling, the contact engaged by brush II3 would be connected to ground through the back contact of line relay H0 and a circuit would thus be established from battery, through motor magnet M, conductor II6, armature I I1, armature H8 and its front contact, armature I24 of motor magnet M and its back contact, through Wiper I I3 and the contact engaged thereby to ground through the back contact of the line relay. Under the condition last assumed, motor magnet M will again be energized to step the brush I I3 to the next contact. During the automatic stepping operation of magnet M, relay I02 will be maintained energized by its circuit through brush I I3, above traced, in parallel with magnet M. Relay I02 being slow to release will not fall off during the brief interruptions to its circuit. Each time motor magnet M energizes, it attracts its armature I24, breaking its own circuit, thus causing the control mechanism to step from position to position so long as brush I I3 engages a grounded contact corresponding to a non-calling line. When, however, it reaches a position corresponding to a calling line, the corresponding contact II4 is free of ground potential and the selecting mechanism will come to rest. The circuit for the stepping magnet M will be opened and relay I 02 will no longer receive current and will fall back breaking its locking circuit.

On the assumption first made, that line I is calling, it is obvious that the selecting mechanism would take but one step before coming to rest. When relay I 02 was actuated, it closed a circuit for relay IOI from battery, through the winding of relay IOI, front contact and armature 7 I20 of relay I02, normal contacts. I2I of relay IOI, over conductor II5 to ground, through the armature of line relay I I0. Relay IOI completed a circuit for the shift relay SR which may be traced from battery, through the winding of SR contacts I62 and I63, conductor I28, armature I29 and front contact of relay IOI, armature I30 and front contact of relay I02 and armature I3I and back contact of relay I05, back to battery. Shift relay SR in operating, closes a circuit for shift magnet S which moves plate III to the right, as shown in Figs. 1 and 2 of the drawings. S also closes contacts 46 When relay IOI attracted its armatures, it interrupted its circuit, first traced, but prepared a substitute circuit which extends from battery, through the winding of relay IOI, through contacts I33, which are now closed due to the energization of shift relay SR thence through armature I34 and front contact of relay IOI and over conductor II5 to ground, through the armature of the line relay. A circuit is now closed for the operating magnet O which extends from battery, through the winding of this magnet, contacts 46 of shift magnet S armature I35 and back contact of relay I 02, through armature I36 and front contact of relay IOI to ground. Magnet 0 in energizing, closes the pairs of contacts of the stack indicated at'a It also closes contacts I6I' and contacts I63 and I64, shown at the opposite ends, respectively,

of the selecting group relay in Fig. 1. It may be here noted that these contacts are actuated whenever magnet O is energized, regardless of which of the stacks a a etc., is selected for operation. Contacts shown at I6I are always closed when magnet O is energized and contact I63 is removed from engagement with contact I62 and into engagement with contactl64.

When the contacts of stack a were actuated, a circuit was completed for relay 20l which may be traced from battery, through the winding of this relay, armature 252 and back contact of relay 205, lowermost pair of contacts of stack a thence over the third line conductor I31 and through the Winding of cutoff relay III, causing the operation of both relays. Relay III, in operating, interrupts the circuit for line relay IIO, the armature of which falls back, removing ground from the start circuit II5 and restoring ground to commutator contact H4 corresponding to line I. When contacts I62 and I63 were opened, due to the energization of magnet 0 the circuit for shift relay SR was interrupted and contact made between I63 and I64 which caused the circuit to be extended through contacts I63* and I66 to the winding of shift relay SR associated with the next selecting group relay B. The deenergization of the line relay H0 interrupted the holding circuit for relay IOI which fell off. When relay 20I became energized, it completed a circuit for relay 202 which may be traced from battery, through one winding of relay 202, armature 2I2 and front contact of relay 20I, conductor 2I3, contacts of the middle pair of stack a conductor I38, over line conductor L through the substation apparatus, back over line conductor L conductor I39, the upper pair of contacts in stack a conductor 2I4, armature 2I5 and front contact of relay 20I, through the other winding of relay 202, back to battery. Thus, relay 202 is bridged directly across'the calling subscriber's line. I

As previously explained, when the commutator brush II3'engaged the contact of the calling assassi- 3 line, ground was absent and magnet M did not pull up. This also interrupted the circuit of relay I02, but as relay I02 is slow-to-release, it did not drop off before ground was applied to the contact engaged by brush I I3 due to the deenergization of line relay IID. Relay IUI having become deenergized, a circuit is now provided from battery through the winding of magnet M, armature III and back contact of relay I05, armature I I8 and front contact of relay I02, armature I 24 and its back contact to the brush II 3 and thence to ground, through the armatures of the line relays of non-calling lines. Tins circuit operates in the same manner as one previously described and magnet M repeatedly energizes and deenergizes until brush II3 arrives at its normal position which is not connected to ground.

When the circuit for shift relay SR was interrupted, it opened the circuit for shift magnet S which in turn permitted the opening of contacts 46a in the circuit of operating magnet However, a holding circuit for magnet O has been closed in the meantime, which extends through contacts IBI, conductor I 40 and armature 2H5 and front contact of relay 29L A circuit now exists for relay 2% which extends from battery, through the winding of 2%, contacts I 65 and I 65, controlled by shift relays SR and SR respectively, conductor 2I8, contact and armature 2) of relay 20I, conductor 229, armature 25I and contact of relay 2I2 and back contact and armature 22! of relay 2! l. A source of dial tone Dial tone is now connected to the calling subscribers line, through the armatures and back contacts of relay 2I2, back contacts and armatures of relay 2| I, armatures and back contacts of relay 2"), to the heavily-shaded conductors which are included in the talking circuit and extend to the calling parties station. The calling subscriber, upon hearing the dial tone, will know that the apparatus is ready to receive the dial impulses.

On the assumption that subscriber on line I is calling the subscriber on line II), he will actuate his dial to open the line circuit ten times, thus causing battery feed relay 202 to be deenergized ten times. Relay 262, at its armature 225 and front contact completed a circuit by way of armature 226 and front contact of relay 234, through the winding of relay I84. Relay I04 in turn completed a circuit from battery, through the winding of relay I65, front contact and armature IAO of relay I04 to ground, through offnormal contact I23 which is now closed. Relay I05, in operating, closed a locking circuit for its circuit by the dial, relay 252 will be deenergized, thus interrupting the circuit of relay I84 which will in turn be deenergized. Each time armature I 42 of relay I64 falls back, it completes a circuit for motor magnet M as follows: from battery, through the winding of magnet M, conductor I I6, armature II! and front contact of relay I 55 and armature I42, back to battery. Thus, motor magnet M will be energized ten times and will step the selecting mechanism to its th position corresponding to the tenth line which is the line to which the connection is desired. The operafunction, will be determined bywhich of the magnets O 0 O or O are actuated. In the present case, the-magnet O of selecting group relay C will be actuated as follows: At the end of the selecting impulses, relay I64 remains energized maintaining a circuit from battery, through the resistance M3, contact and armature of relay I04, winding of relay I05 and off-normal contact I 23 which is now closed. The continued flow of current through resistance I43 causes relay Hi6 to become energized. A circuit had previously been provided for shift relay SR from battery, through the winding of this relay, conductor IM, armature 230 and front contact of relay 204 and front contact and armature I II of relay I05. Relay SR closed the circuit for shift magnet S which shifted plate ID and closed contacts 43 in the same manenr as connected with selecting group relay A. Thus, when relay I06 attracted its armature, it closed a circuit through the winding of magnet 0 contacts 46, conductor I45, armature Hi6 and front contact of relay I08, causing plate II] of selecting group relay C to' be tilted, thus actuating the tenth contact stack 0 When magnet O attracted its armature, it closed a locking circuit for itself from battery, through its winding contacts I6I, contact 23I of relay 2i I, thence over conductors I47 and I46, back to batter through armature 2E6 and front contact of relay 21H. Whenever the test or lowermost pair of contacts of one of the stacks of selecting group relay 0 are closed, a circuit is completed from battery through the winding of relay 206, conductor 232 to all of the lowermost springs of selecting relay 0. In the present case, this circuit is continued through the resting spring of the lowermost pair of stack c thence over conductor I48 and through the cut-off relay I49 of line I8. This causes relay 206 to operate. A circuit is also completed at this time for test relay 2"] which extends from battery, through both windings of this relay, through normal contacts of relay 2| I, conductor 233, armature 234 of relay 205, conductor 232 and thence to ground, through cutoff relay I49 as in the circuit traced above. The flow of current through relays 206 and 2H) to relay I 49 causes the latter relay to operate. If the line is idle, relay 2'I0 is energized.

When relay 2I0 becomes energized, it completesa circuit from batterythrough the winding of relay 2| I, armaturefllil and front contact of relay 2), conductor 233, armature 234 and back contact of relay 2% and thence to ground through the winding of cutoff relay Hi9. Relay 2m, in operating, closes a locking circuit for itself which extends from battery, through its winding, armature 2M and front contact, conground through armature 22I and front contact of relay 2. when it attracts its relay 2I2 which in turn closed one point in the circuit from-the source of busy tone BT. If relay 2I0 had not operated, the circuit from busy tone B'I would have been extended through back con-, tacts and armatures of relay 2H and back contacts and armatures of relay 2H) to, the heavilyshaded conductors which extend to the calling line. However, on the assumption that the called line is idle, relay 2I0 is energized and cutsofi the source of busy tone ET in an obvious manner. Had the called line been busy, the high resistance winding of relay 210 would have been in parallel with the low resistance winding of relay 2II of the other link, in which case, relay 2I0 would not have received sufficient current to attract its armatures.

Assuming that the line is idle, relay 2H1 pulls up and completes a circuit from battery, through the winding of ringing interrupter relay 209, through contact and armature of relay 2I0 to interrupter INT. Relay 203 in attracting its armature 235, connects the source of ringing tone RT to the calling line. Through its armature 236, it connects one side of the source of ringing energy 231 to a heavily-shaded conductor extending to the called line and at armature 239 it connects the other side of the source of ringing energy, through resistance 238 to the other heavily-shaded conductor extending to the called line. The ringing current from source 231 flows through the winding of ringing cutofi relay 208, armature 236 and front contact of interrupter relay 209, armature 246 and front contact of relay 2II, contacts of stack of selecting relay C, thence out over one side of line I0,through the substation apparatus on line I0, back over the other side of the line, through the companion contacts of 0 of selecting relay C, armature 241 and front contact of relay 2| I, armature 230 and resistance 238, back to the source of current.

When the called party answers, the increased flow of current through the winding of relay 208 causes it to attract its armature, interrupting the circuit through contacts 202, thus breaking the locking circuit for relay 2 I 0 which thereupon returns to its normal position. If the called party answers during a silent period, relay 201 will be energized causing ringing current to be cut off in an obvious manner. When relay 209 falls back, following the response of the called subscriber, battery feed relay 201 is bridged across the called line and, due to the decreased resistance of the line, it attracts its armatures. At its armature 248, it closes a path in parallel with armature 234 of relay 205 in the holding circuit of relay 2I I. Thus, the circuit of relay 2 is now controlled in part at the substation of the called line. The subscribers are now connected for conversation.

Upon the cessation of the selecting impulses sent by the calling subscriber, relay magnet O was energized which caused relay 205 to become energized in series with cutoff relay I49 as previously described. Relay 206 in turn completed a circuit for relay 2I2. Relay 204, which has been maintained energized in a circuit including a back contact and armature 25I of relay 2I2 now becomes deenergized and at its armature 220, interrupts the circuit for the relay I04. Relay I04 in retracting its armatures, interrupts the holding circuit for relay I05 causing its armature to be retracted. The circuit is now completed from battery through the winding of motor magnet M, armature H1 and back contact of relay I05, armature I I8 and front contact of relay I02, armature I24 and its resting contact brush I I3 and contact I I4 engaged theremature of the called line. Thus, electromagnet M is energized and steps the selecting mechanism around, in a manner previously described, until brush II3 engages a contact II4 which is not grounded. If at this time no other line is calling, the selecting mechanism will return to its normal position.

After the conversation has been terminated, the subscribers will replace their receivers upon the switch hooks which will open the respective line circuits. The opening of the line circuit of the subscriber on line I interrupts the circuit for battery feed relay 202 and it retracts its armatures. The opening of the hook switch on line I0 interrupts the circuit for battery relay 201 which becomes deenergized. At this time, relay I is held up in series with the cutoff relay III of line I and relay 206 is in similar manner energized in series with cutoff relay I49 of line I0. A circuit is now completed from battery, through the winding of relay 205, armature and back contact of relay 203, armature 249 and front contact of relay 20I to ground, through armature 262 and front contact of relay 2I2. Relay 205 attracts its armature 234 which opens the holding circuit for relay 2 as armature 248 by to ground through the back contact and arof relay 201 had previously fallen back. Relay 2 thereupon becomes deenergized and at its armature 22I, interrpts the circuit for relay 205 which likewise falls back. When relay 205 attracted its armature 252, it interrupted the circuit for relay 20I which became deenergized and at its armature 2I6, removed the ground from conductor I40 through which magnet O was I locked up.

, When magnet O was first operated, its locking circuit included the ground at armature 2I5 of relay 20I but when relay 2II became energized, a substitute locking circuit for magnet O was provided through armature 250 of relay 2II so long as this relay remained energized. Upon the falling back of relays 2H and 20I, the selecting relay magnets O and 0 both become deenergized as the lead from the normally closed contacts of relay 20I is open at this time at the back contact of armature 253 of slow release relay 205.

As previously explained, the selecting group relay A is the answering end of one link, while the selecting relay C is the terminating end of said link. This connecting circuit has been designated as link I. In exactly the same manner, the originating end of link 2 terminates in selecting group relay B and terminates in selecting relay D. Of course, it is to be understood that more than two pairs of relays A, C or, B,'D may be provided so that more than two links are available for the ten lines. Also, the number of lines in the group may be considerably increased without departing in any way from the mode of operation herein described.

If a call is initiated by another line while line I and line I0 are connected by link I, the selecting circuit will function in exactly the same manner in connection with link 2, as above described in connection with link I. Should a second line call, the start wire II5 will be grounded through the line relay of the calling line which will actuate relay I03 and the other relays as above described. But as the plate ID of select ing relay A is due to the continued energization of magnet 0 contact I83 will be separated from its lower associated contact I62 maintained in operated position,

and in engagement with its upper contact I64.- Thus, instead of shift relay SR being operated, as above described, conductor I28 will be extended over conductor I50, then through the resting contacts I53 and I64 at the right in selecting relay B and through the winding of relay SR to battery. Thus, if a second call is initiated, relay SR will operate causing the operation of shift magnet S which in turn will cause the energization of magnet O of selecting relay B.

It is obvious, from the above description, that the selecting mechanism comprising the commutator shaft, magnet M and the controlling circuits therefor, are common to the several link circuits which may be provided and are at all times in normal position, except when actually employed in establishing a connection.

Should a subscriber call a busy line and neglect to replace his receiver upon its hook, the selecting mechanism will return to its normal position as soon as the connection has been established. It will be recalled that relay 206 was energized in series with the cutoff relay I49 of the called line as soon as the power magnet O was energized. Relay 2I2 then was actuated and, thus, would interrupt the circuit for relay 294. Relay 204 in turn interrupted the circuit of relay I04 causing relay I95 to fall back, completing the previously traced circuit for the motor magnet M, through the armature II! and its back contact, armature H8 and its front contact and interrupter armature I24 of the stepping magnet. Thus, the selector will be stepped around until the contact of another calling line is engaged or until it reaches normal position.

Should a second subscriber call before the first calling subscriber has completed his connection, it will have no effect on the apparatus until the power magnet O or at the terminating end of the link employed, has operated responsive to the dial impulses sent by the first calling subscriber, at which time relay 20% operates in series with the cutoff relay of the called line. Upon connection being made to a calling line, relays I84 and I of the control mechanism are maintained energized until after the selecting impulses are sent by the calling subscriber. Thus, although the line last calling will have placed ground on start lead II5, it will have no effect as the circuit for magnet M will be open at the armature II! and back contact of relay I05 and no operation will take place. As soon, however, as the magnet O or O of the terminating selecting relay has actuated, relay 296 will operate, causing relays 204, I84 and I05 to fall off and the selector will again start its operation as above described.

. In the present disclosure, the operation of applicants connecting mechanism has been illustrated in a system having but a single group of lines. However, the mechanism and principles of operation herein disclosed may readily be adapted to systems having a plurality of line groups or to large exchange systems in which several stages of selection are required.

The relay and selecting mechanism herein disclosed will be found to operate in a satisfactory manner and they represent a structure which applicant, at present, considers a preferred embodiment of his invention. It is obvious, however, that many modifications may be made in the details of both the structure and the operating circuits. The invention should, therefore, be limited only by the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure byLetteis Patent of the United States is:

1. In a line connecting apparatus, a relay including more than two contact sets, an electromagnet and an armature therefor, common tov said contact sets and an electromagnetically operated selective means for operatively associating said armature with a single desired one of said contact sets, whereby the said desired contact set will be actuated to the exclusion of all other said contact sets by energization of said electromagnet.

2. In a line connecting apparatus, a relay including a plurality of contact sets, a plurality of displaceable arms for said relay, one for each set of contacts, an electromagnet, an armature for said electromagnet arranged to displace the said arms toward said contacts upon actuation thereof, a shaft rotatably mounted adjacent to said arms, cams spirally positioned on said shaft, there being a cam for each arm, said cams being arranged to successively shift the said arms one after another into registry with their respective contact sets upon rotation of. said shaft and electromagnetic means for rotating said shaft to operatively associate an arm with a desiredcontact set whereby the contacts of said desired set will be actuated to the exclusion of all others as aresult of the energization of the electromagnet of said relay.

3. In a line connecting apparatus, a relay including a plurality of contact sets, a plurality of displaceable arms, one for each of said contact sets, a rotatable shaft adjacent to said arms, means carried by said shaft, arranged to selectively shift said arms into registry with their respective contact sets incident to rotation of said shaft, electromagnetic means for rotating said shaft, an operating electromagnet for said relay, an armature for said magnet arranged to actuate said plurality of arms by energization of said. operating magnet, whereby the contacts of the selected contact set are actuated.

4. In a line connecting apparatus, a relay in cluding a plurality of contact sets arranged in a row, there being a plurality of pairs of related contacts in each set, a plurality of displaceable arms, one for each said contact set, a rotatable shaft adjacent to said arms, cams spirally arranged on said shaft, one for each of said arms, said cams being arranged to selectively shift said arms into registry with their respective contact sets incident to rotation of said shaft, means for rotating said shaft, an operating electromagnet for said relay, and an armature for said magnet arranged to displace said plurality of arms by energization of said operating magnet, whereby the contacts of the selected contact set are actuated.

5. In a line connecting apparatus, a plurality of relays, each including-a plurality of contact sets, an electromagnet and an armature therefor, individual to each relay, each electromagnet and its armature being common to the contact sets of a relay, an electromagnetically actuated selective means common to said relays for operatively associating an armature with a desired one of said contact sets, whereby the contacts of said desired set will be actuated to the exclusion of all other sets as a result of the energization of the electromagnet of the corresponding relay.

6. In a line connecting apparatus, a plurality of relays, each including a plurality of contact sets, an electromagnet and an armature therefor, individual to each relay,--each electromagnet and its armature being common to the contact sets of a relay, an electromagnetically operated selective means for operatively associating an armature with a single desired one of said contact sets, whereby the contacts of said desired set will be actuated upon energization of the electromagnet of the corresponding relay, means for retaining the contacts of said set in actuated position and means permitting the contemporaneous operation of said selective means to select a desired contact set in another of said relays.

7. In a line connecting apparatus, a plurality of relays, each relay including a plurality of contact sets, a plurality of arms for each relay, one for each set of contacts, electromagnets, one for each relay, an armature for each electromagnet common to the arms of the corresponding relay and arranged to displace said arms toward their respective contact sets upon actuatin thereof, a shaft, an electromagnet for actuating said shaft and means carried by said shaft arranged to selectively shift said. arms into operative relation to their respective contact sets, whereby the contacts of a desired set will be actuated as a result of the energization of the electromagnet of the corresponding relay.

8. In a line connecting apparatus, a plurality of relays, each relay including a plurality of contact sets, a plurality of displaceable arms for each relay, one for each set of contacts, electromagnets, one for each relay, an armature for each electromagnet common to the arms of the corresponding relay, arranged to displace said arms upon actuation thereof, a shaft rotatably mounted adjacent to said arms, electromagnetic means for rotating said shaft and means carried by said shaft, effective incident to actuation thereof, for selectively shifting said arms into operative relation to their respective contact sets whereby the contacts of a desired set may be actuated as a result of the energization of the electromagnet of the corresponding relay.

9. In a line connecting apparatus, a plurality of relays, each relay including a plurality of contact sets, a plurality of displaceable arms for each relay, one for each set of contacts, electromagnets, one for each relay, an armature for each electromagnet common to the arms of the corresponding relay, a shaft rotatably mounted adjacent to said arms, electromagnetic means for rotating said shaft and means carried by said shaft arranged to selectively shift the arms into operative relation to their respective contact sets upon rotation of said shaft, whereby the contacts of a desired set may be actuated by energization of the electromagnet of the corresponding relay.

10. In a line connecting apparatus, a plurality of relays, each relay including a plurality of contact sets, a plurality of arms for each relay, one for each set of contacts, electromagnets, one for each relay, an armature for each electromagnet common to the arms of the corresponding relay and arranged to displace said arms upon actuation thereof, a shaft, an electromagnet for actuating said shaft, means carried by said shaft arranged to selectively shift said arms into operative relation to their respective contact sets, whereby the contacts of a desired set may be actuated upon energization of the electromagnet of the corresponding relay, means for returning said shaft to normal position and means for retaining the actuated contact set in actuated position.

11. In a line connecting apparatus, a plurality of relays, each relay including a plurality of can tact sets, a plurality of displaceable arms for each relay, one for each set of contacts, electromagnets, one for each relay, an armature for each electromagnet common to the arms of the corresponding relay, a shaft rotatably mounted adjacent to said arms, electromagnetic means for rotating said shaft, means carried by said shaft arranged to selectively shift the said arms into operative relation to their respective contact sets upon rotation of said shaft, whereby the contacts of a desired set may be actuated upon energization of the electromagnet of the corresponding relay, means for returning said shaft to normal position and means for retaining the actuated contact set in actuated position.

12. In a line connecting apparatus, a plurality of relays, each relay including a plurality of contact sets, a plurality of arms for each relay, one for each set of contacts, electromagnets, one for each relay, an armature for each electromagnet common to the arms of the corresponding relay and arranged to displace said arms upon actuation thereof, a shaft, an electromagnet for actuating said shaft, means carried by said shaft arranged to selectively shift said arms into operative relation to their respective contact sets, whereby the contacts of a desired set may be actuated upon energization of the electromagnet of the corresponding relay, means for retaining the contacts of the actuated set inactuated posi-- tion and means permitting the contemporaneous operation of said shaft to select a desired contact set in another of said relays.

13. In a line connecting apparatus, a plurality of relays, each relay including a plurality of contact sets, a plurality of displaceable arms for each relay, one for each set of contacts, electromagnets, one for each relay, an armature for each electromagnet common to the arms of the corresponding relay, arranged to displace said arms upon actuation thereof, a shaft rotatably mounted adjacent to said arms, electromagnetic means for rotating said shaft, means carried by said shaft, effective incident to rotation thereof, for selectively shifting said arms into operative relation to their respective contact sets whereby the contacts of a desired set will be actuated upon energization of the electromagnet of the corresponding relay, interengaging means on said arms and contact sets for retaining the arm of an actuated contact set in shifted position and means permitting the contemporaneous operation of said shaft to select a desired contact set in another of said relays.

14. In a line connecting apparatus, a relay, including a plurality of contact sets, an electromagnet for said relay, an armature for said electromagnet, displaceable arms, one for each contact set, carried by said armature, a shaft mounted adjacent to said arms, means for actuating said shaft, and means carried by said shaft arranged to selectively shift one of said arms into registry with a desired contact set upon actuation of said shaft, so that the contacts of said desired set will be actuated incident to energization of said electromagnet.

15. In a line connecting apparatus, a relay, including a plurality of contact sets, an electromagnet for said relay, an armature for said electromagnet, a plurality of displaceable arms carried by'said armature, one for each contact set,a.shaf.t rotatably mounted adjacent to said arms,.means for rotating said shaft, a group of cams spirally positioned on said shaft, there be,

ing a cam for each arm, said cams being arranged to selectively shift the said arms into operative relation to their respective contact sets upon rotation of said shaft, whereby the contacts of a desired set will be actuated upon energization of said electromagnet.

16. In a line connecting apparatus, a plurality of relays, each relay including a plurality of contact sets, electromagnets, one for each relay, an armature for each electromagnet, a plurality of displaceable arms carried by each armature, one for each contact set of a relay, a shaft, means for actuating said shaft and means carried by said shaft arranged upon actuation thereof, to selectively shift said arms into operative relation to their respective contact sets, whereby the contacts of a desired set will be actuated upon energization of the electromagnet of the corresponding relay.

1'7. In a telephone system, a link circuit, relays, one at each end of said link circuit, in which said link circuit terminates, a plurality of contact sets in each relay, subscribers lines terminating in the respective contact sets of each of said relays, a single actuating magnet for each relay, selecting mechanism, means actuated responsive to the initiation of a call on one of said lines for causing said selecting mechanism to associate the single contact set of the relay at the answering end of said link circuit in which said calling line terminates with the corresponding actuating magnet for operation thereby, and means responsive to substation control for actuating said selecting mechanism to associate the single contact set of the relay at the other end of said link circuit in which the wanted line terminates with the actuating magnet of said other relay for operation thereby.

18. In a telephone system, a plurality of link circuits, relays, one at each end of each of said link circuits in which said link circuits respectively terminate, a plurality of contact sets in each relay, lines terminating in said contact sets, a single actuating magnet for each relay, selecting mechanism, means actuated responsive to an incoming call on one of said lines for causing said selecting mechanism to associate the contact set of the relay at the answering end of one of said link circuits in which said calling line terminates with the corresponding actuating magnet for operation thereby, and means responsive to substation control for actuating said selecting mechanism to associate the contact set of the relay at the other end of said link circuit in which the desired outgoing line terminates with the actuating magnet of said other relay for operation thereby.

19. In a telephone system, a plurality of link circuits, relays, one at each end of each of said link circuits in which said link circuits respectively terminate, a plurality of contact sets in each relay, lines terminating in said contact sets, a single actuating magnet for each relay, selecting mechanism, means actuated responsive to an incoming call on one of said lines for causing said selecting mechanism to associate the contact set of the relay at the answering end of one of said link circuits in which said calling line terminates with the corresponding actuating magnet for operation thereby, means responsive to substation control for actuating said selecting mechanism to associate the contact set of the relay at the other end of said link circuit in which the desired outgoing line terminates with the actuating magnet of said other relay for operation thereby, and means for thereupon freeing said selecting mechanism for use in establishing a connection from another incoming line to an outgoing line through another link circuit and its terminating relays.

20. In a telephone system, a plurality of link circuits, relays, one at each end of eachof said link circuits in which said link circuits respectively terminate, a plurality of contact sets in each relay, subscribers lines terminating in said contact sets, a single actuating magnet for each relay, selecting mechanism, means actuated responsive to the initiation of a call on one of said lines for causing said selecting mechanism to associate the contact set of the relay at the answering end of one of said link circuits in which said calling line terminates with the corresponding actuating magnet for operation thereby, means responsive to substation control for actuating said selecting mechanism to associate the contact set of the relay at the other end of said link circuit in which the wanted line terminates with the actuating magnet of said other relay for operation thereby, and means for thereupon freeing said selecting mechanism for use in establishing a connection from another calling line to another called line through another link circuit and its terminating relays.

21. In a telephone'system, a plurality of link circuits, relays, one at each end of each of said link circuits in which said link circuits respectively terminate, a plurality of contact sets in each relay, subscribers lines terminating in the respective contact sets of each of said relays, a single actuating magnet for each relay, selecting mechanism, means actuated responsive to the initiation of a call on one of said lines for causing said selecting mechanism to associate the contact set of the relay at the answering end of one of said link circuits in which said calling line terminates with the corresponding actuating magnet for operation thereby, means respon-- sive to substation control for actuating said se-' lecting mechanism to associate the contact set of the relay at the other end of said link circuit in which the wanted line terminates with the actuating magnet of said other relay for operation thereby, and means for thereupon freeing said selecting mechanism for use in establishing a connection from another calling to another called line through another link circuit and its associated relays. 1

22. In a telephone system, a plurality of link circuits, relays, one at each end of each of said link circuits in which said link circuits respectively terminate, a plurality of contact sets in each relay, subscribers lines terminating in the respective contact sets of each of said relays, a single actuating magnet for each relay, a single selecting mechanism common to said relays, means actuated responsive to the initiation of a call on one of said lines for causing said selecting mechanism to mechanically associate the contact set of the relay at the answering end of one of said link circuits in which said calling line terminates with the corresponding actuating magnet for operation thereby, means responsive to substation control for actuating said selecting mechanism to mechanically associate a contact set of the relay at the other end of said link circuit in which the wanted line terminates with the actuating magnet of said other relay for operation thereby, and means for thereupon freeing said selecting mechanism for use in establishing a connection from another calling line to another called line through another link circuit and its terminating relays.

23. In a telephone system, relays, each having a plurality of contact sets and a common actuating magnet, subscribers lines terminating in said contact sets, control mechanism, effective upon initiation of a call on one of said lines to associate a contact set of one of said relays in the contacts of which the calling line terminates with its respective actuating magnet for operation thereby, and responsive to sub-station control for associating a contact set of one of said relays in which the wanted line terminates, with its actuating magnet for operation thereby and link circuit means for inter-connecting the actuated contact sets.

24. In a circuit controlling apparatus, pairs of contact springs arranged, respectively, in cooperatively engageable relation, a plurality of displaceable arms, one for each pair of springs, a selecting device adjustably mounted adjacent to said arms, means for operating said device, means on said device, effective upon actuation thereof, for selectively displacing said arms into registry with their respective pairs of springs, an actuating member common to said arms, and an electromagnet for operating said actuating member, said actuating member being arranged, upon actuation thereof by said electromagnet, to move a displaced arm into operative engagement with r a pair of springs whereby a desired pair of springs may be brought into operative relation by the energization of said electromagnet.

25. In a circuit controlling apparatus, pairs of contact springs arranged, respectively, in cooperatively engageable relation, a plurality of displaceable arms, one for each pair of springs, a selecting device adjustably mounted adjacent to said arms, means for operating said device, means carried by said device, effective upon actuation thereof, for displacing said arms, one by one, into registry with their respective pairs of springs, an actuating member common to said arms, and an electromagnet for operating said actuating member, said actuating member being arranged, upon actuation thereof by said electromagnet, to move a displaced arm into operative engagement with a pair of springs whereby a desired pair of springs may be brought into operative relation by the energization of said electromagnet.

26. In a circuit controlling apparatus, pairs of contact springs arranged, respectively, in cooperatively engageable relation, a plurality of displaceable arms, one for each pair of springs, a r:

selecting device adjustably mounted adjacent to said arms, means for operating said device, means on said device, effective upon actuation thereof, for selectively displacing said arms in one direction into registry with their respective pairs of springs, an actuating member common to said arms, and an electromagnet for operating said actuating member, said actuating member being arranged, upon actuation thereof by said electromagnet, to move a displaced arm in a different direction into operative engagement with a pair of springs whereby a desired pair of springs may be brought into operative relation by the energization of said electromagnet.

27. In a circuit controlling apparatus, pairs of contact springs arranged, respectively, in cooperatively engageable relation, a plurality of displaceable arms, one for each pair of springs, a shaft adjustably mounted adjacent to said arms, cams on said shaft, effective upon actuation thereof, for selectively and successively displac-' ing said arms into registry with their respective pairs of springs, an actuating member common to said arms, and an electromagnet for operating said actuating member, said actuating member being arranged, upon actuation thereof by said electromagnet, to move a displaced arm into operative engagement with a pair of springs whereby a desired pair of springs may be brought into operative relation by the energization of said electromagnet.

28. In a circuit controlling apparatus, pairs of contact springs arranged, respectively, in cooperatively engageable relation, a plurality of displaceable arms, one for each pair of springs, a shaft rotatably mounted adjacent to said arms, means for rotating said shaft, means on said shaft, effective upon actuation thereof, for selectively displacing said arms in one direction into registry with their respective pairs of springs, an actuating member common to said arms, and an electromagnet for operating said actuating member, said actuating member being arranged, upon actuation thereof by said electromagnet, to move a displaced arm in a transverse direction into operative engagement with a pair of springs whereby a desired pair of springs may be brought into operative relation by the energization of said electromagnet.

29. In a circuit controlling apparatus, pairs of contact springs arranged, respectively, in cooperatively engageable relation, a plurality of displaceable arms, one for each pair of springs, a shaft rotatably mounted adjacent to said arms, means for rotating said shaft, cams on said shaft, effective upon rotation thereof, for selectively displacing said arms into alignment with their respective pairs of springs, an actuating member common to said arms, and an electromagnet for operating said actuating member, said actuating member being arranged, upon actuation thereof by said electromagnet, to move a displaced arm into operative engagement with a pair of springs whereby a desired pair of springs may be brought into operative relation by the energization of said electromagnet.

30. In a circuit controlling apparatus, pairs of contact springs arranged, respectively, in cooperatively engageable relation, a plurality of displaceable arms, one for each pair of springs, a shaft mounted adjacent to said arms, means for actuating said shaft, means on said shaft, effective upon actuation thereof, for selectively displacing said arms in one plane into registry with the respective pairs of springs, an actuating member common to said arms, and an electromagnet for operating said actuating member, said actuating member being arranged, upon actuation thereof by said electromagnet, to move a displaced arm in an intersecting plane into operative engagement with a pair of springs whereby a desired pair of springs may be brought into operative relation by the energization of said electromagnet.

31. In a circuit controlling apparatus, pairs of contact springs arranged, respectively, in cooperatively engageable relation, a plurality of displaceable arms, one for each pair of springs, a shaft rotatably mounted adjacent to said arms, means for rotating said shaft, cams on said shaft, effective upon rotation thereof, for selectively displacing said arms one by one in one plane into registry with their respective pairs of springs, an actuating member common to said arms, and an electromagnet for operating said actuating member, said actuating member being arranged,

upon actuation thereof by said electromagnet, to move a displaced arm in an intersecting plane into operative engagement with a pair of springs whereby a desired pair of springs may be brought into operative relation by the energization of said electromagnet.

32. In a telephone system, a plurality of relays, a plurality of contact sets in each relay, lines terminating respectively in said contact sets of each of said relays, an actuating magnet for each relay, selecting mechanism common to said relays and means actuated responsive to the initiation of a call on one of said lines for causing said selecting mechanism to associate the single contact set of an idle one of said relays in which said calling line terminates with the corresponding actuating magnet for operation thereby.

33. In a telephone system, a plurality of relays, a plurality of contact sets in each relay, subscribers lines terminating in the respective contact sets of each of said relays, an actuating magnet for each relay, selecting mechanism, control means actuated, responsive to the initiation of a call on one of said lines, for causing said selecting mechanism to associate the single contact set of one of said relays in which the calling line terminates with the corresponding actuating magnet for operation thereby, and means responsive to the initiation of a call on another of 4 said lines for actuating said selecting mechanism to associate the single contact set of another relay in which the second calling line terminates with the actuating magnet of said other relay for operation thereby.

34. In a telephone system, a plurality of relays, a plurality of contact sets in each relay, lines terminating respectively in contact sets of each of said relays, an actuating magnet for each relay, selecting mechanism common to said relays, means actuated responsive to the initiation of a call on one of said lines for causing said selecting mechanism to associate the contact set of an idle relay in which said calling line terminates with the corresponding actuating magnet for operation thereby, means for thereupon freeing said selecting mechanism and means responsive to the initiation of a call on another of said lines for actuating said selecting mechanism to associate the single contact set of another of said relays in which the second calling line terminates with the actuating magnet of said other relay for operation thereby.

35. In a telephone system, relays, a plurality of contact sets in each relay, lines terminating respectively in contact sets of each of said relays, an actuating magnet for each relay, means actuated responsive to the initiation of a call on one of said lines for associating the contact set of an idle relay in which said calling line terminates with the corresponding magnet for operation thereby, said means being actuated in response to the initiation of a call on another of said lines for associating the contact set of a now idle relay in which the second calling line terminates with the corresponding magnet for operation thereby.

36. In a telephone system, relays, a plurality of contact sets in each relay, subscribers lines terminating in the respective contact sets of each of said relays, an actuating magnet for each relay, selecting mechanism common to said relays, means actuated responsive to the initiation of a when one of said lines for associating one of said relays with the calling line, means responsive to substation control for actuating said selecting mechanism to associate the contact set of the said one of said relays in which awanted subscribers line terminates with the actuating magnet of the said relay for operation thereby, and means for thereupon freeing said selecting mechanism for use in establishing a connection from another calling line to another called line through another of said relays.

37. In a telephone system, relays, a plurality of contact sets in each relay, subscribers lines terminating in the respective contact sets of each of said relays, an actuating magnet for each relay, selecting mechanism common to said relays, means actuated responsive to the initiation of a call on one of said lines for associating one of said relays with the calling line, means controlled over said line for actuating said selecting mechanism to associate the contact set of the said one of said relays in which the wanted subscribers line terminates with the actuating magnet of the said relay for operation thereby, means for thereupon freeing said selecting mechanism, and means for associating a second one of said relays with a second calling line, said selecting mechanism being now controllable over said second calling line to actuate said selecting mechanism to associate the contact set of said second one of said relays in which the second wanted subscribers line terminates with the actuating magnet of said second one of said relays for operation thereby.

38. In a telephone system, relays, a plurality of contact sets for each relay, each set comprising pairs of contact springs arranged, respectively, in cooperatively engageable relation, a plurality of displaceable arms, one for each pair of springs, a selecting device adjustably mounted adjacent to said arms, means for selectively moving said device, shift means on said.

device, effective upon movement thereof, for selectively displacing said arms one by one in one plane into registry with their respective pairs of springs, an actuating member common to said arms, and an electromagnet for operating said actuating member, said actuating member being arranged, upon actuation thereof by said electromagnet, to move a displaced arm in an intersecting plane into operative engagement with a pair of springs whereby the springs of a desired pair may be brought into operative relation by the energization of said electromagnet.

39. In a line connecting apparatus as set forth in claim 1, said means including laterally displaceable arms mounted on and carried by said armature, one for each of said contact sets; any one of said sets of contacts being rendered actuatable by said armature, incidental to energization of said electromagnet, responsive to lateral displacement of the associated arm; and means for laterally displacing the arm corresponding to any desired contact set.

40. In a line connecting apparatus as set forth in claim 1., said means including arms pivotally mounted on and carried by said armature, one for each of said contact sets; any one of said sets of contacts being rendered actuatable by said armature, incidental to energization of said electromagnet, responsive to rotation of the associated arm about its pivot; and means for rotating the arm corresponding to any desired contact set.

41. In a line connecting apparatus as set forth in claim 1, said contact sets being arranged in a row along said armature, but not directly actuatable thereby when the armature moves incidental to energizaticn of said electromagnet, said armature having a row of arms adjustably mounted thereon for movement therewith and corresponding respectively to said contact sets, each arm having a normal position in which it does not engage and operate its corresponding contact set when the armature is moved by said electromagnet, each arm having a position of adjustment in which it contacts and actuates its corresponding contact set when moved by the armature, and means for moving any desired one of said arms from its said normal position to its said position of adjustment.

GEORGE R. EATON. 

